Known circuits for converting AC power to DC power, such as rectifier networks with passive input and output filters, produce significant harmonic distortion of the AC current waveforms. Harmonic distortion causes undesirable power dissipation and creates unwanted electromagnetic interference which couples into other lines and equipment. Distorted AC current waveforms also excite undesirable vibrational modes in electromagnetic couplings. In addition, input power factor is adversely affected resulting in decreased operating efficiency.
Still other known AC to DC power conversion approaches involve active circuits utilizing various pulse width modulated switching mode techniques. Such pulse width modulation techniques produce discrete circuit current pulses at the modulation frequency which require substantial filtering to limit harmonic distortion and electromagnetic interference. Substantial filtering adds to the weight of the conversion circuit, requires additional space, increases costs, and makes it difficult to achieve near unity power factor.